The present disclosure relates to fuel injection strategies for opposed-piston engines with direct side injection. In particular, the present disclosure concerns fuel injection in opposed-piston cylinders equipped with multiple injectors.
Efficient combustion is a fundamental challenge inherent in diesel engine operation. This challenge is typically addressed in conventional diesel engines by injecting fuel from a central location on the fire deck directly into an appropriately shaped combustion chamber defined between the end surface of the piston and the fire deck.
In opposed-piston architecture, two pistons are disposed crown to crown in a cylinder where they move in opposition between top dead center (TDC) and bottom dead center (BDC) positions. The combustion chamber is defined in the cylinder, between the end surfaces of the pistons as they approach TDC. Consequently, it is not possible to mount a fuel injector in a central position facing the end surface of a piston in an opposed-piston engine. Instead, a fuel injector mounting site is typically located on the sidewall of the cylinder, between the TDC locations of the piston end surfaces. This results in the direct side injection configuration that is characteristic of opposed-piston engine design. That is to say, fuel is injected directly into the combustion chamber, through the sidewall of the cylinder.
A problem with direct side injection is that the injected fuel travels radially or tangentially into the cylinder, transversely to the axis of charge air swirl, which can inhibit air/fuel mixing and result in incomplete and/or uneven combustion. Accordingly, it is desirable to improve the fuel injection capabilities of opposed-piston engines with direct side injection.